Plastic parts of an opening device such as a cover, a tap, and a cap can be applied on a container or packaging.
A method of applying plastic parts includes forming a plastic part by extrusion molding or injection molding using various molds (e.g., metal molds) in advance and, applying the plastic part with heat-sealing/adhesive on the packaging container. A method is also known for molding a plastic part directly to an opening top edge, simple container side walls, and a top of a cup-shaped container including, e.g., flexible web materials. However, the use of this method is limited.
A container such as the octagonal-shaped container 1 of FIG. 3 can be obtained by forming a tube from flexible web material, filling the tube with liquid food, transverse sealing of the tube material, cuffing, folding flaps to the container top and, forming the final shape.
In manufacturing a folded container having folded flaps on the container top, a primary container 51 is obtained by cuffing of sealed tube-like material along a crease line, as shown in FIG. 5 (a). Final container 1, with an octagonal pillar shape, is obtained by triple foldings, as shown in FIG. 5 (b), to container top 53 of folding flaps 52, as shown in FIG. 5(c).
For example, in the container as shown in FIG. 7, the folded flaps 52 are folded on the container top wall 53. There are gaps between the folded flaps and the container top wall, gaps between the folded flaps and the other folded flaps, steps between the container top walls, and steps between the folded flaps. The container does not have a simple design. When the plastic parts of a cover, etc., are applied to the container top wall, the design of the plastic parts and the container may be limited.
In a container having folded flaps, the flaps are folded by using flexible web materials with crease lines, and folding along the crease lines. Further manufacturing processes, energy, material, and equipment are necessary when using adhesive or heat sealing to fix the folded flaps to the container top wall.
In a container having the flaps folded on the container top wall, dust, garbage, and small insects can stick in the gaps and steps referred to above when the container is being delivered.